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The ASUS A7M266-D is the only board coming without any on-board USB interface and neither does it have any integrated network controller. As mentioned earlier, the integrated USB 1.1 works just fine in almost any application as long as it is enabled so it is somewhat surprising to see the ports gone completely, which leaves ASUS without the backdoor to simply turn USB ON again.

ASUS A7M266D
Onboard CMedia 6-channel Sound, no USB ports at all and no integrated Ethernet controller but the most sophisticated power circuitry. Note that there is no game port either but then, the board is not geared towards the gaming community anyway.

The A7M266-D features the CMedia CMI 8738 six-channel integrated sound, which, especially on a MPX board layout cannot be underestimated since the two 64 bit PCI slots cannot be used for standard PCI cards. One slot will, in almost all configurations be used for the USB 2.0 PCI card with the NEC controller chip placed on the expansion card, a second slot needs to be allocated to PCI Ethernet adapter which leaves a single PCI slot for any other card. Considering that this is a workstation board, in most cases we will look at a IEEE 1394 or specialty sound card like e.g. DigiDesign or similar or else an additional PCI graphics card.

To conclude, the A7M266-D features integrated sound but completely lacks USB and network interfaces unless they are added in the form of PCI cards. On the other hand, the AGP interface uses the Pro slot with additional power for high-end cards.

Power Supply And Circuitry

It is somewhat surprising to see the EZ Plug missing from the A7M266-D since we have found this interface for the supply of auxiliary power a very nifty addition to the ASUS P4 boards. Instead, we see the 4-prong ATX 2.03 dual 12V connector and the somewhat old-fashioned AT-aux power 6-prong connector. Especially the 12V Aux connector is necessary, we have more on that on the next page.

Circuitry Map Of The A7M266D

The real estate covered by the power circuitry of the primary CPU (CPU0) is shaded in turquoise, the circuitry of the secondary CPU (CPU1) in yellow. The two HIP6301 regulators are marked with a "1".

In terms of the voltage regulator circuitry, ASUS offers a unique solution in that the A7M266-D sports two completely separate voltage control circuitries, each using its own Intersil HIP 6301 triple-phase controller chip, three driver chips and six MOSFETs. Aside from custom tailoring the supply current for each CPU depending on the respective demand, this also allows to set the core voltage for CPU0 manually via jumpers to offset the higher workload in most applications for the primary CPU without affecting the secondary CPU.

In most cases, though, the OS turns out to be smart enough to toggle between the two processors in applications that don't support SMP.

An amicable side effect of this extremely sophisticated power circuitry is that there is very little need for capacitors and, thus, the sockets are readily accessible for mounting of any heatsink. One caveat here is that, like in the case of the A7M266E, the board itself is protected by a credit card thick piece of clear plastic that can cause some issues with getting the necessary clearance for sliding the heatsink clip under the bracket.

A misconception about SMP systems is that applications that don't utilize it will only access a single CPU. The screenshot of the CPU usage history in 3DMark2001SE shows that the load is balanced between the two CPUs at any time, however will never exceed 50% total CPU usage. In other words, even in applications that only use a "single CPU" there is a distribution of the total workload between both CPUs, however, the busier one CPU is, the less load will go to the second CPU and the sum of both activities will be 50% of the total system CPU power.

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